Sri Lanka, Feb. 24 -- Storm clouds are gathering over Australia's T20 World Cup campaign, with unseasonal Perth rain threatening to spoil what looms as a must-win clash for the defending champions today.

Australia need to defeat Sri Lanka at the WACA Ground to give themselves the best chance of advancing to the knock-out stage of the tournament, after dropping their first group game to India in Sydney on Friday.

Meg Lanning's team have never been beaten by their eighth-ranked opponents in any format and while there's no discounting the threat posed by hard-hitting Sri Lanka Captain Chamari Atapattu, Australia go into the match as red-hot favourites to collect their first two points of the campaign.

However, the Bureau of Meteorology wa...